1. Field of the Invention
This invention relates to a steering wheel, particularly to a steering wheel with a horn switch assembled within a horn pad which is located substantially at the center thereof.
2. Description of the Related Art
A steering wheel or a horn switch is disclosed in Japanese Laid Open Utility Model Publication No. 60-823, Japanese Laid Open Utility Model Publication No. 60-34052, and Japanese Laid Open Utility Model Publication No. 60-133542.
FIG. 3 shows a cross section of a conventional horn switch, while FIG. 4 shows a cross section of another conventional horn switch.
In the figures, a pad cover 1 is made of soft synthetic resin. An insert 2 is made of hard synthetic resin. The insert 2 is assembled integrally on the backside of the pad cover 1 to form a horn pad 3. A fixing frame 4 is made of metal and adapted to secure the insert 2. A sheet member 5 is also made of metal and disposed in a space 51 between the pad cover 1 and the fixing frame 4. A contact 6 is fitted to the sheet member 5 as a positive electrode. A contact 7 is supported on the fixing frame 4 as a negative electrode. The contacts 6 and 7 are arranged on opposite positions so as to be able to touch each other. These contacts 6 and 7 constitute contact means for a switching operation in an electric circuit for a horn.
A flanged spacer 9 is made of an electrical insulating material and has its flange engaged with the sheet member 5 to regulate movement thereof in the direction toward the pad cover 1. Thus, the sheet member 5 is supported via the spacer 9 in a movable manner relative to the fixing frame 4. A screw 10 secures the spacer 9 to the fixing frame 4. The fixing frame 4 has a through hole 11 formed therein that has a larger dimension than a dimension of the outer circumference of the spacer 9. The spacer 9 is slidably inserted into the through hole 11.
FIG. 3 shows a leaf spring 8 which urges the sheet member 5 toward the pad cover 1. An insulating sheet 12 is interposed between the leaf spring 8 and the fixing frame 4.
In FIG. 4, a coil spring 13 urges the sheet member 5 toward the pad cover 1 similarly to the leaf spring 8. The coil spring 13 is held between the fixing frame 4 and the sheet member 5 through a spring seat 14 formed of electric insulating material.
The horn switches of steering wheels, in the prior art, are constructed as above and assembled within the horn pad 3 composed of the pad cover 1 and the insert 2. In the normal state or when the horn switch is off, the positive contact 6 and the negative contact 7 are separated from each other by a predetermined distance.
To operate the horn switch, a driver pushes the pad cover 1 from the outside with a prescribed pressure so that the pad cover 1 is deformed to blow the horn. That is, as the pad cover 1 is deformed, the sheet member 5 inside thereof is moved toward the fixing frame 4 against the urging force of the spring 8 or spring 13. Then, the contacts 6 and 7 are touched together so as to close the electric circuit for the horn, thereby sounding the horn.
The horn pad 3 accommodating therein the horn switch is usually located substantially at the center of the steering wheel.
All elements of the switching device are assembled on the fixing frame 4 in the conventional horn switch as constructed above. On the other hand, the sheet member 5 with the contact 6 fixed thereto is movably supported in the space 51 between the pad cover 1 and the fixing frame 4 with the contact 7 secured thereto. Therefore, there must be provided some special insulating members like the spacer 9, insulating sheet 12 and spring seat 14, in order to electrically isolate the sheet member 5 and the fixing frame 4, both of which are made of metal.
Moreover, the insert 5 is fitted to the periphery of the backside of the pad cover 1 to form the horn pad 3 in the conventional horn switch. Thus, the insert 5 mainly serves as a support to hold the pad cover 1 while acting as a fixing member to secure the horn pad 3 to the fixing frame 4.
Consequently, the horn switch of the prior art inevitably has many parts and a complicated structure. Thus, the assembling thereof to the steering wheel is troublesome, an improvement of which is desirable.